The invention relates to an aerosol container and to a method for storage and administration of a predetermined amount of a pharmaceutically active aerosol in accordance with the respective independent patent claim.
Aerosols are today a common dosage form for pharmaceutically active substances. Many of those aerosols are to be administered in predetermined (metered) amounts. For various reasons (for example stability), certain pharmaceutically active substances are supplied in the form of a suspension, that is to say the pharmaceutically active substance is present in the aerosol container, usually under pressure, in the form of small solids particles in a liquid, the liquid also comprising at least a propellant gas. That kind of formulation of pharmaceutically active substances has proved suitable for many substances, and especially also for corticosteroids.
In order to administer a predetermined amount of the pharmaceutically active substance, customary aerosol containers are provided with a metering valve having a metering chamber. In a first position of the valve, the metering chamber is in communication with the interior of the container and, in that position, has been filled with the predetermined amount of suspension. In a second position of the metering valve, the amount disposed in the metering chamber is then released in the form of an aerosol, since the liquid/solid mixture can expand. In that manner the aerosol can be administered, for example orally or nasally, to the user.
Hitherto, the propellant gases used have been the widely known fluorochlorohydrocarbons. Those chlorinated propellant gases are now known to be harmful, since they destroy the ozone layer, and they therefore should, and must, be abolished and replaced by other propellant gases that do not damage the ozone layer. In some countries, very recently those propellant gases which comprise chlorinated hydrocarbons have even been banned by law.
So-called xe2x80x9calternative propellant gasesxe2x80x9d are therefore presented as an alternative, since they do not damage the ozone layer (ozone-depleting potential=0). However, many pharmaceutical substances, when stored in the form of a suspension, are deposited on the inner wall of the container when those propellant gases are used, whereas that did not occur, or occurred only to a very small extent, when chlorinated hydrocarbons were used. Such deposits on the inner wall of the container may result in the desired amount of pharmaceutical active substance that is to be administered to the user not being present in the metering chamber. A further consequence is that the total amount of pharmaceutically active substance stored in the container cannot be administered, since a very considerable proportion of the total amount of pharmaceutically active substance introduced into the container remains deposited on (adheres to) the inner wall of the container.
The aim of the invention is therefore to provide a container in which the pharmaceutically active substance can be supplied in the formulation that has already proved suitable and in which, at the same time, it is possible for alternative propellant gases that do not damage the ozone layer to be used, without significant amounts of the pharmaceutically active substance being deposited on the inner wall of the container. In particular, that is to be possible for anti-asthmatically active pharmaceutical substances (for example corticosteroids), but of course the intention is for it also to be possible for other classes of pharmaceutical substances to be stored in such containers without any significant deposits of active substance being deposited on the inner wall of the container.
The aim is achieved in accordance with the invention by a container in which the inner wall is coated with a plastics coating and in which the propellant gas is a propellant gas that is free of fluorochlorohydrocarbons, preferably a propellant gas that comprises only fluorohydrocarbons and, where appropriate, also cosolvents and/or surfactants. With such an arrangement, on the one hand no or no significant amounts of active substance are deposited on the inner wall of the container, and on the other hand the ozone layer is not damaged or destroyed. Especially advantageous materials that may be used for the plastics coating are, for example, polytetrafluoroethylene, widely known as Teflon, and also perfluoroethylenepropylene.